Such a capacitor is described in German Unexamined Patent Application (Offenlegungsschrift) No. 14 64 695. In particular, in FIG. 4 of that application and in the corresponding description, a disc-shaped barrier layer capacitor is shown in which a reoxidation layer on one main surface of the capacitor is ground away.
A process for producing a barrier layer capacitor in which formation of a reoxidation layer on a main surface of the capacitor body is avoided in advance is known from German Patent No. 12 82 791. In that case, two discs of semi-conductive material are detachably connected by a non-oxidizing substance before the application of the barrier layer free coatings. In both of the above mentioned cases, the reduction layer extends to a main surface of the disc-shaped capacitor body.
A barrier layer capacitor in which the reduction layer extends to the outer surface of the disc-shaped capacitor body is known from U.S. Pat. No. 3,133,338. Particularly in FIG. 7 and in the corresponding description, a circuit arrangement of barrier layer capacitors is disclosed. The reduction layer extends to the entire outer surface of the disc-shaped capacitor body and is contacted free of a barrier layer there. In this case, grinding or cutting is necessary along the entire outer surface.
Applicant's German Provisional Patent (Auslegeschrift) No. 2 320 482 discloses a barrier layer capacitor in which the reduction layer extends only to a part of the outer surface of a disc-shaped capacitor body. It is provided there with a barrier layer free electrode coating. A second electrode coating covers at least both main surfaces of the capacitor body, except for a coating free region which extends parallel to the barrier layer free coating surface. Although the capacitor body is relatively easy to produce, the electric contacting is problematical because of the de-doping resistance at the barrier layer free coating surface.
Also known in the art is a ceramic capacitor having a capacitor body with a cross-section that is developed in the shape of a flat tube. The body has a central inner borehole. On the outer grounding surface of the body, metal layers are the coatings or electrodes of the capacitor. These are known from German Provisional Patent (Auslegeschrift) No. 1 904 677, German Unexamined Application for Patent (Offenlegungsschrift) No. 2 043 770, German Provisional Patent (Auslegeschrift) No. 2 345 000 and German Utility Model (Gebrauchsmuster) No. 7 101 847. However, in all of these known forms of capacitors having a cross-section in the shape of a flat tube, the central inner bore contains a metal coating and a capacitor connection. The introduction of both these is difficult during manufacture. As a result, the connection elements do not extend symmetrically away from the capacitor body.
In the capacitor shown in German Provisional Patent (Auslegeschrift) No. 2 345 000, a capacitor connection in the inner bore is not absolutely necessary. In such a case, however, the total capacitance between the two capacitor connections is relatively small as a result of the series connection of two individual capacitances.
German Unexamined Application for Patent (Offenlegungschrift) No. 2 404 758 discloses a process for mass producing electric components. The body of such a component has a solid rectangular cross-section. There is a longitudinal groove on each of two opposite narrow sides of the body. A connecting element is fastened into each groove. However, that application relates to resistors or ceramic capacitors and not to the barrier layer capacitors of the present invention.
U.S. Pat. No. 3,001,106 discloses a compact circuit system having connection components with asymmetrical and symmetrical cross-sectional profiles in the form of a flat tube, as shown in FIGS. 2 and 2d thereof. In that case also, a connecting element is contained in the inner bore and the disclosure does not concern a barrier layer capacitor.